R help - Apr 2006 - What does "rbind(iris[,,1], iris[,,2], iris[,,3])" do?

It's in the Venables & Ripley MASS (ed 3) book in the section on
principal components.
The context is as follows
> ir <- rbind(iris[,,1], iris[,,2], iris[,,3])
> ir.species <-
factor(c(rep("s",50),rep("c",50),rep("v",50)))
(then they use brush(ir) which I guess is not an R function)

and then
> princomp(log(ir[1:4]),cor=T)
(there is no [1:4] in the text which is probably a typo)
>From what I can see,
> iris[,,1]
is the same as
> iris
and "rbind(iris[,,1], iris[,,2], iris[,,3])" duplicates iris 3 times
while "mangling" the row index. What happens to the index and what is
the purpose of that?

I also seem to get the same result with "rbind(iris[,,1], iris[,,1],
iris[,,1])". What is the difference with "rbind(iris[,,1], iris[,,2],
iris[,,3])"?

'iris' in S-PLUS is not the same as 'iris' in R, rather similar
to 'iris3'
in R.

You need the fourth (2002) edition of the book to work with R.

The book does say in many places (including its title) it is about 
'S-PLUS', but does have on-line complements about the changes needed for
R
of a similar vintage (last updated Dec 2001).

You are trying to use a book written in 1998 on a different system in 
2006, and you have the audacity to accuse the authors of making errors
because it does not work.  I look forwards to receiving your apology.


On Thu, 13 Apr 2006, Sasha Pustota wrote:
> It's in the Venables & Ripley MASS (ed 3) book in the section on
> principal components.
> The context is as follows
>
>> ir <- rbind(iris[,,1], iris[,,2], iris[,,3])
>> ir.species <-
factor(c(rep("s",50),rep("c",50),rep("v",50)))
> (then they use brush(ir) which I guess is not an R function)
>
> and then
>
>> princomp(log(ir[1:4]),cor=T)
> (there is no [1:4] in the text which is probably a typo)
No, just your error.
>> From what I can see,
>
>> iris[,,1]
>
> is the same as
>
>> iris
>
> and "rbind(iris[,,1], iris[,,2], iris[,,3])" duplicates iris 3
times
> while "mangling" the row index. What happens to the index and
what is
> the purpose of that?
>
> I also seem to get the same result with "rbind(iris[,,1], iris[,,1],
> iris[,,1])". What is the difference with "rbind(iris[,,1],
iris[,,2],
> iris[,,3])"?
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

What you are referring to iris is called iris3 in R so just replace
iris with iris3.   iris3 is a 3d array in R whereas iris is a data frame.

On 4/13/06, Sasha Pustota <popgen at gmail.com>
wrote:
> It's in the Venables & Ripley MASS (ed 3) book in the section on
> principal components.
> The context is as follows
>
> > ir <- rbind(iris[,,1], iris[,,2], iris[,,3])
> > ir.species <-
factor(c(rep("s",50),rep("c",50),rep("v",50)))
> (then they use brush(ir) which I guess is not an R function)
>
> and then
>
> > princomp(log(ir[1:4]),cor=T)
> (there is no [1:4] in the text which is probably a typo)
>
> >From what I can see,
>
> > iris[,,1]
>
> is the same as
>
> > iris
>
> and "rbind(iris[,,1], iris[,,2], iris[,,3])" duplicates iris 3
times
> while "mangling" the row index. What happens to the index and
what is
> the purpose of that?
>
> I also seem to get the same result with "rbind(iris[,,1], iris[,,1],
> iris[,,1])". What is the difference with "rbind(iris[,,1],
iris[,,2],
> iris[,,3])"?
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>

[Gabor Grothendieck]
>What you are referring to iris is called iris3 in R so just replace
>iris with iris3.   iris3 is a 3d array in R whereas iris is a data frame.
Thanks for this calm and simple reply.  Some could learn from you! :-)

-- 
Fran?ois Pinard   http://pinard.progiciels-bpi.ca